Vibration damping mount and metal heat shield

ABSTRACT

The present invention provides a vibration damping mount with which a vibration damping action is improved and also provides a metal heat shield with which a sound insulation performance is improved. The vibration damping mount includes: a substantially annular damping member that has an insertion hole, through which the bolt to be attached to an attachment boss is inserted, and externally surrounds the bolt; a grommet that includes a first retaining section for retaining a heat shield, a second retaining section for retaining the damping member, and a coupling section for coupling the first retaining section and the second retaining section, the second retaining section, the coupling section, and the first retaining section being provided in this order from the attachment boss side; and a collar member that includes a pair of flange sections, which nip the damping member from both sides in an axial direction with gaps formed on both the sides, and a coupling section, which couples the pair of flange sections each other and has a gap in a radial direction between the coupling section and the damping member.

BACKGROUND OF THE INVENTION

The present invention relates to a vibration damping mount that is usedfor mounting, for example, a heat shield or a housing on a membergenerating a vibration or heat, and relates to a metal heat shield thatcan be attached to, for example, an exhaust manifold of an internalcombustion engine using such a vibration damping mount.

A heat shield, which is an example of such a metal exhaust manifold heatshield or housing, is used in an automobile. Such a heat shield, forexample, a part near an exhaust manifold mounted on an engine of anautomobile so as to control heat and sound from the exhaust manifold notto propagate to the periphery of the engine. Such a heat shield isattached to the exhaust manifold by a screw member such as a bolt.

FIG. 2 is a front view of an engine 1 of a vehicle such as an automobileshowing a basic structure of this conventional technique. FIG. 40 is asectional view of the conventional technique. The conventional techniquewill be hereinafter explained with reference to both FIGS. 2 and 40. Anexhaust manifold 2 is attached to a side of the engine 1 in order todischarge a combustion exhaust gas. A heat shield 3 is attached to theexhaust manifold 2 so as to cover this exhaust manifold 2.

The heat shield 3 is mounted in order to control heat and sound, whichis generated from the exhaust manifold 2 as a pulsating combustionexhaust gas passes through the inside of the exhaust manifold 2, not topropagate to the periphery of the engine 1. Consequently, as shown inFIG. 40, the heat shield 3 has a structure in which a damping member 6having heat insulating properties is nipped by an inner 4 and an outer 5consisting of a metal plate, respectively. As this damping member 6, aninorganic fibrous material or an inorganic porous material is used.

A structure for attaching such a heat shield 3 to the exhaust manifold 2will be explained as follows with reference to FIG. 40. In the heatshield 3, an insertion hole 8 for inserting a bolt 7 is formed, and adisk-like washer 9 is arranged. The bolt 7 is inserted through thewasher 9 and the heat shield 3 and screwed to an attachment boss 10 ofthe exhaust manifold 2. Consequently, the heat shield 3 is attached tothe exhaust manifold 2.

As an example of the heat shield 3 of the above -mentioned conventionaltechnique, an heat shield disclosed in a published documentJP-A-10-266850 is known. The heat shield of JP-A-10-266850 isconstituted by placing two steel sheets one on top of the other.

The heat shield with such a structure is heavy, and a momentum of avibration of the heat shield due to a vibration, which is transmittedfrom an exhaust manifold via a bolt or the like, increases.Consequently, a problem occurs in that a crack tends to be caused in aportion where the heat shield is attached to the bolt or the like, anddurability is deteriorated.

In addition, in the case in which it is attempted to improve a soundinsulation performance in such an heat shield, it is possible that aplate thickness is increased to control a degree of transmission ofnoise in the heat shield. However, in this case, a weight increases asdescribed above. Therefore, there is a problem in that it is difficultto improve the sound insulation performance with such a conventionaltechnique.

Further, the conventional technique has problems as described below. Inthe case in which the heat shield 3 is attached to the exhaust manifold2 as shown in FIG. 40, concerning a vibration that is generated from theexhaust manifold 2 and transmitted through the bolt 7, it is difficultto absorb a vibration component in a direction crossing an axis of thebolt 7 indicated by arrow A3 in FIG. 40. Due to propagation of such avibration component, the heat shield 3 produces resonance, or metalfatigue is caused around the portion where the bolt 7 of the heat shield3 is attached. Consequently, problems such as an increase of noise andformation of a crack in the heat shield 3 occur, and a problem arises ina quality of the heat shield 3.

Moreover, concerning heat generated from the exhaust manifold 2, otherthan radiant heat from the exhaust manifold 2 to the heat shield 3, heatis transmitted to the heat shield 3 via the bolt 7.

In the heat shield 3 shown in FIG. 40, since the bolt 7 is in directcontact with the washer 9, and the washer 9 is in direct contact withthe heat shield 3, the heat from the exhaust manifold 2 is easilytransmitted to the heat shield 3. Consequently, temperature of the heatshield 3 rises, and the radiant heat increases to easily damage, forexample, auxiliary devices, ducts, and harnesses around the engine 1 ina hood due to heat. Therefore, a problem arises in a quality as a heatshield.

As one of techniques for solving such problems, a technique shown inFIG. 41 is possible. FIG. 41 is a sectional view showing a vibrationdamping mount 11 that is used for attaching the heat shield 3 to theexhaust manifold or the~like. A structure of the vibration damping mount11 will be hereinafter explained.

A collar 12 is mounted in an insertion hole 8 of the heat shield 3. Thecollar 12 includes a cylindrical coupling section 13 and a pair offlange sections 14 and 15 that are formed integrally at both ends of thecoupling section 13, respectively, and expand outwardly in a radialdirection thereof. A distance between the flange sections 14 and 15 isformed larger than a thickness of the heat shield 3. Damping sheets 16and 17, which are made of, for example, a felt-like body consisting ofstainless steel fiber or an expand metal of stainless steel, areinserted between each of the flange sections 14 and 15 and the heatshield 3.

In other words, the flange sections 14 and 15 of the collar 12 nip andhold the pair of damping sheets 16 and 17 that nip the heat shield 3.The bolt 7 is inserted through the collar 12 and screwed into anattachment boss of exhaust manifold 2. Consequently, the heat shield 3is attached to the exhaust manifold 2 via the vibration damping mount11.

In this technique, a vibration, which has traveled from the bolt 7 tothe collar 12, is transmitted to the damping sheets 16 and 17 andabsorbed by compression and restoration actions in an axial direction ofthe bolt 7 of the damping sheets 16 and 17. Consequently, in thistechnique, a vibration to be transmitted from the bolt 7 to the heatshield 3 is controlled.

On the other hand, in such a technique shown in FIG. 41, the dampingsheets 16 and 17 deteriorate due to secular changes and self weightsthereof. Consequently, it is assumed that a problem may occur in thatthe compression and restoration characteristics of the damping sheets 16and 17 are degraded and the action of controlling a vibration isdegraded. In addition, since the damping sheets 16 and 17 are formed ofthe inorganic fiber, the expand metal, or the like, it is assumed that aproblem may occur in that the fiber decomposes and flies as timeelapses. In these regards, it is considered that the technique shown inFIG. 41 has a problem in that a quality with respect to a vibrationdamping action is low.

Moreover, as a yet another conventional technique for solving theseproblems, a vibration damping mount disclosed in, for example, apublished document JP-A-2002-235800 is known. FIG. 42 is a sectionalview of a vibration damping mount 11 b that is disclosedJP-A-2002-235800. The vibration damping mount 11 b of the conventionaltechnique will be hereinafter explained with reference to FIG. 42.Components in FIG. 42 corresponding to the components, which havealready been explained, will be denoted by the identical referencenumerals and signs and will not be explained anew.

The vibration damping mount 11 b includes: a substantially annulardamping member 18 formed of stainless steel or the like that is providedexternally surrounding the bolt 7; and a grommet 20 formed of aluminumalloy and having substantially an S shaped section that serves as acoupling component. The grommet 20 has an insertion hole 19 throughwhich the bolt 7, which is screwed into the attachment boss 10 or thelike of the exhaust manifold 2, is inserted.

The grommet 20 includes: a first retaining section 20 a having a shapewith an inner peripheral edge of a circular metal plate folded back toan outer peripheral portion in order to retain the heat shield 3; asecond retaining section 20 b having a shape with an outer peripheraledge of the circular metal plate folded back to an inner peripheralportion in order to retain the damping member 18; and a coupling section20 c that is formed bending over the first retaining section 20 a andthe second retaining section 20 b and couples the heat shield 3 and thedamping member 18 via the first retaining section 20 a and the secondretaining section 20 b. In addition, the collar 12 formed of agalvanized steel plate is provided between an inner periphery of thedamping member 18 and the bolt 7. Gaps are provided in an axialdirection and a radial direction of the bolt 7 between the collar 12 andthe damping member 18.

In the vibration damping mount 11 b having such a structure, avibration, which is generated from the exhaust manifold 2 and travelsthrough the bolt 7, is transmitted to the heat shield 3 via the dampingmember 18 and the grommet 20. This vibration is attenuated by actions ofthe damping member 18 and the grommet 20.

However, such conventional techniques have problems to be explainedbelow. It is known that the attachment boss 10, to which the bolt 7 isattached, is often formed in a size overlapping the grommet 20 asindicated by an alternate long and two short dash lines in FIG. 42. Insuch a case, since the grommet 20 and the attachment boss 10 are incontact with each other, noise due to this contact increases. Inaddition, it is assumed that contact portions of the grommet 20 and theattachment boss 10 wear with time due to this contact to result inbreakage. Consequently, a problem arises in a quality of the vibrationdamping mount 11 b.

In addition, on the basis of a difference of the materials of the collar12, the damping member 18, and the grommet 20, a electrical current dueto a difference of ionization tendencies of aluminum and stainless steelis generated between aluminum on a surface of the grommet 20 andstainless steel of the damping member 18, and electrolysis may occur inthe grommet 20 and the damping member 18. Consequently, it is likelythat the grommet 20 and the damping member 18 are broken. As a result,again, a problem arises in the quality of the vibration damping mount 11b.

BRIEF SUMMARY OF THE INVENTION

The present invention has been devised in order to solve the problemsinherent in the heat shield and the vibration damping mount of theconventional techniques. It is an object of the present invention toprovide a vibration damping mount with which the breakage due to wearingand the occurrence of electrolysis are prevented and the vibrationdamping action is improved remarkably and to provide a metal heat shieldwith which the sound insulation performance is improved remarkably.

A vibration damping mount according to an aspect of the presentinvention is a vibration damping mount that is arranged between pluralobject members, which are coupled each other using a screw member suchas a bolt, and damps transmission of a vibration from one object member,which becomes a vibration source, to the other object member,characterized by including:

a substantially annular damping member that has an insertion hole,through which the screw member to be attached to the one object memberis inserted, and is provided externally surrounding the screw member;

a coupling member that has an insertion hole through which the screwmember to be attached to the one object member is inserted, and includesa first retaining section for retaining the other object member, asecond retaining section for retaining the damping member, and acoupling section for coupling the first retaining section and the secondretaining section, the second retaining section, the coupling section,and the first retaining section being provided in this order from theone object member side; and

a collar member that is arranged between the screw member and thedamping member and includes a pair of flange sections, which nip thedamping member from both sides in an axial direction with gaps formed onboth the sides, and a coupling section, which couples the pair of flangesections each other and has a gap in a radial direction between thecoupling section and the damping member.

A vibration damping mount according to another aspect of the presentinvention is a vibration damping mount that is arranged between pluralobject members, which are coupled each other using a screw member suchas a bolt, and damps transmission of a vibration from one object member,which becomes a vibration source, to the other object member,characterized by including:

a plural plate-like damping members stacked one on top of another andformed of an iron alloy that have an insertion hole, through which thescrew member to be attached to the one object member is inserted, havefilms formed on surfaces thereof, the films containing at least a metalor a metal compound with an ionization tendency closer to that ofaluminum than that of iron, and nip the other object member near anouter peripheral portion thereof so as to be displaceable in a radialdirection; and

a collar member that includes a pair of flange sections, which arearranged between the screw member and the damping members so as to bedisplaceable in a radial direction and an axial direction with respectto the damping members and nip the plural damping members from bothsides in the axial direction with gaps formed on both the sides, and acoupling section for coupling the pair of flange sections.

A vibration damping mount according to yet another aspect of the presentinvention is a vibration damping mount that is arranged between pluralobject members, which are coupled each other using a screw member suchas a bolt, and damps transmission of a vibration from one object member,which becomes a vibration source, to the other object member,characterized by including:

a plural plate-like damping members formed of an iron alloy and stackedone on top of another that have an insertion hole, through which thescrew member to be attached to the one object member is inserted, havefilms formed on surfaces thereof, the films containing at least a metalor a metal compound with an ionization tendency closer to that ofaluminum than that of iron, and nip the other object member near anouter peripheral portion thereof so as to be displaceable in a radialdirection, the part near the outer peripheral portion being formed as afree end that vibrates freely; and

a collar member that includes a pair of flange sections, which arearranged between the screw member and the damping members so as to bedisplaceable in a radial direction and an axial direction with respectto the damping members and nip the plural damping members from bothsides in the axial direction, and a coupling section for coupling thepair of flange sections.

A vibration damping mount according to yet another aspect of the presentinvention is a vibration damping mount that is arranged between pluralobject members, which are coupled each other using a screw member suchas a bolt, and damps transmission of a vibration from one object member,which becomes a vibration source, to the other object member,characterized by including:

a damping member formed of an iron alloy that has an insertion hole,through which the screw member to be attached to the one object memberis inserted, has a film formed on a surface thereof, the film containingat least a metal or a metal compound with an ionization tendency closerto that of aluminum than that of iron, and includes a coupling section,which is coupled to the other object member, and a vibration section,which is an area separated from the other object member and the screwmember and is allowed to be bent and displaced.

A vibration damping mount according to yet another aspect of the presentinvention is a vibration damping mount that is arranged between pluralobject members, which are coupled each other using a screw member suchas a bolt, and damps transmission of a vibration from one object member,which becomes a vibration source, to the other object member,characterized by including:

a spacer that has a substantially cylindrical base section having aninsertion hole, through which the screw member to be attached to the oneobject member is inserted, and a sliding section, which integrallycontinues outwardly in a radial direction of the base section and has apair of sliding surfaces, a distance between which in an axial directiondecreasing toward a outside in the radial direction;

a nip member that is arranged outwardly in a radial direction of thespacer and includes a pair of nip pieces, which are arrangedincreasingly spaced apart from each other in the axial direction from anoutside in the radial direction toward an inside in the radialdirection, the pair of nip pieces consisting of a material having aspring property, which elastically nips the sliding section of thespacer from sides opposed to each other on the inside in the radialdirection, and being allowed to be displaced from each other at least inthe radial direction with respect to the spacer; and

a coupling member that includes a first retaining section for retaininga part near an end in the outside in the radial direction of the nipmember, a second retaining section for retaining the other objectmember, and a coupling section for coupling the first retaining sectionand the second retaining section, the first retaining section, thecoupling section, and the second retaining section being provided inthis order from the one object member side.

A metal heat shield according to yet another aspect of the presentinvention is a metal heat shield that includes one or more aluminumalloy plates, on which corrugate shapes extending in directions crossingeach other are formed, and forms a three-dimensional shape,characterized in that a flange section is provided at least in one partof an outer peripheral part of the three-dimensional shape, and thecorrugate shapes in a crush object portion including the flange sectionare crushed to be formed in a substantially tabular shape, and

one of the directions crossing each other is set in a direction crossinga main ridge equivalent portion constituting the three-dimensionalshape.

According to an aspect of the present invention, a vibration from theone object member is transmitted through the screw member, the collarmember, the damping member, and the coupling member. In addition, thesecond retaining section, the coupling section, and the first retainingsection of the coupling member are provided in this order from the sideof the one member that is a vibration source. In other words, the firstretaining section is located on the opposite side of the one objectmember with respect to the damping member.

Therefore, even in the case in which an attachment portion of the oneobject member with respect to the screw material has a size in a radialdirection overlapping the coupling member, a situation in which theattachment portion of the one object member comes into contact with thecoupling member or the other object member retained by this couplingmember is prevented. Consequently, an increase in noise due to thecontact is controlled.

In addition, in the case in which contact of the attachment portion andthe coupling member or the other object member is assumed, it is assumedthat a contact portion of the coupling member with the attachmentportion wears due to this contact to result in breakage. Occurrence ofsuch breakage is prevented in this aspect of the present invention.Consequently, a quality of the vibration damping mount is improvedremarkably.

According to another aspect of the present invention, the plate-likedamping members have the films, which contain at least a metal or ametal compound having an ionization tendency closer to that of aluminumthan that of iron, formed on the surfaces thereof. Therefore, even inthe case in which the collar member or the like, with which the dampingmembers are in contact, is constituted by iron or a metal having anionization tendency close to that of iron, occurrence of electrolysis isprevented, and a quality of the vibration damping mount can be improvedremarkably.

According to yet another aspect of the present invention, the filmscontaining at least a metal or a metal compound having an ionizationtendency closer to that of aluminum than that of iron are formed on thesurfaces of the plate-like damping members formed of an iron alloy andstacked one on top of another that nip the other object member near anouter peripheral portion thereof so as to be displaceable in a radialdirection, the part near the outer peripheral portion being formed as afree end that vibrates freely. Therefore, actions and effects same asthose described above can be realized.

According to yet another aspect of the present invention, the filmcontaining at least a metal or a metal compound having an ionizationtendency closer to that of aluminum than that of iron is formed on thesurface of the damping member formed of an iron alloy that includes thecoupling section, which is coupled to the other object member, and thevibration section, which is an area separated from the other objectmember and the screw member and is allowed to be bent and displaced.Therefore, actions and effects same as those described above can berealized.

According to yet another aspect of the present invention, vibration,which occurs in the one object member, is transmitted to the otherobject member via the spacer, the nip member, and the coupling member.In this aspect of the present invention, the sliding section on theoutside in the radial direction of the spacer is nipped by the pair ofnip pieces of the nip member elastically. The spacer and the nip memberare allowed to be displaced from each other in the radial direction.Therefore, when the spacer vibrates in the radial direction, the nipmember and the spacer are displaced from each other in the radialdirection while the pair of nip pieces move along the sliding section ofthe spacer. Consequently, the vibration in the radial direction of thespacer is absorbed by the mutual displacement in the radial direction ofthe spacer and the nip member.

In addition, the nip member has a spring property. Therefore, vibrationin the axial direction of the spacer is absorbed by vibration in theaxial direction of the nip member.

Consequently, the vibration of the spacer is absorbed by the spacer andthe nip member, and a degree of transmission of vibration from the oneobject member to the other object member can be controlled remarkably.

According to yet another aspect of the present invention, the firstdirection of the plural corrugate shapes formed on the metal heat shieldis set in the direction crossing the major ridge equivalent portion.Thus, the corrugate shapes realize a function of a rib with respect to avibration around the ridge equivalent portion.

On the other hand, when the metal heat shield is mounted against avibration source, the metal heat shield is also vibrated by transmissionof a vibration from the vibration source. When the metal heat shield isvibrated by this vibration, it is known that portions of the metal heatshield on both sides of the major ridge equivalent portion tend tovibrate to flop around the portion.

In this aspect of the present invention, vibration of the metal heatshield can be controlled by the rib action. Therefore, occurrence of acrack in the metal heat shield can be prevented, and a quality of themetal heat shield can be improved remarkably.

In addition, in this aspect of the present invention, the flange sectionis formed at least in a part of the outer peripheral portion of themetal heat shield having a three-dimensional shape. Thus, this flangesection realizes a function of a rib with respect to vibration at thetime of vibration of the metal heat shield. Consequently, a vibrationcharacteristic of the metal heat shield is also improved.

Further, in this aspect of the present invention, the corrugate shapesof the crush object portion including the flange section of the metalheat shield are crushed to be formed in a substantially tabular shape.Thus, in the case in which bending work, drilling work, or inscriptionwork for the outer peripheral portion of the metal heat shield isperformed, an object portion of the work can be treated in the samemanner as a tabular metal plate. Therefore, workability in manufacturingthe metal heat shield having such a structure is improved.

BRIEF DESCRIPTION OF THE DRAWINGS

In the accompanying drawings:

FIG. 1 is a sectional view of a vibration damping mount 21 according toa first embodiment of the present invention;

FIG. 2 is a front view of an engine 1 showing a structure forming abasis of the present invention;

FIG. 3 is a sectional view of the engine 1 viewed from a section lineX3-X3 in FIG. 2;

FIG. 4 is an enlarged front view of a heat shield 1;

FIG. 5 is a sectional view of the heat shield 1 viewed from a sectionline X5-X5 in FIG. 4;

FIG. 6 is a sectional view of the heat shield 1 viewed from a sectionline X6-X6 in FIG. 4;

FIG. 7 is a sectional view of the heat shield 1 viewed from a sectionline X7-X7 in FIG. 4;

FIG. 8 is a simplified sectional view of the engine 1 viewed from asection line X8-X8 in FIG. 2;

FIG. 9 is a view illustrating characteristics of this embodiment;

FIG. 10 is a sectional view schematically showing a vibration dampingmount 21 a according to a second embodiment of the present invention;

FIG. 11 is a sectional view showing a principle of this embodiment;

FIG. 12 is an enlarged sectional view showing the principle of thisembodiment;

FIG. 13 is a graph showing an effect of this embodiment;

FIG. 14 is a sectional view of a vibration damping mount 21 b accordingto a third embodiment of the present invention;

FIG. 15 is a sectional view of a comparative example of this embodiment;

FIG. 16 is a sectional view showing characteristics of the vibrationdamping mount 21 b;

FIG. 17 is a plan view of spring washers 23 and 24 of the vibrationdamping mount 21 b;

FIG. 18 is a perspective view of the spring washers 23 and 24;

FIG. 19 is a perspective view of a comparative example with respect tothe vibration damping mount 21 b;

FIG. 20 is a sectional view of the comparative example;

FIG. 21 is a sectional view showing an operational example of thevibration damping mount 21 b;

FIG. 22 is a sectional view showing another operational example of thevibration damping mount 21 b;

FIG. 23 is a sectional view showing yet another operational example ofthe vibration damping mount 21 b;

FIG. 24 is a graph illustrating an action of this embodiment;

FIG. 25 is a sectional view showing a modification of the firstembodiment;

FIG. 26 is a sectional view of a vibration damping mount 21 c accordingto a fourth embodiment of the present invention;

FIG. 27 is a graph illustrating an action of this embodiment;

FIG. 28 is a sectional view of a vibration damping mount 21 d accordingto this embodiment;

FIG. 29 is a plan view of the vibration damping mount 21 d;

FIG. 30 is a front view of a spacer 90 that is used in this embodiment;

FIG. 31 is a plan view of the spacer 90;

FIG. 32 is a sectional view of a nip member 97 that is used in thisembodiment;

FIG. 33 is a plan view of the nip member 97;

FIG. 34 is a sectional view of a vibration damping mount 21 e of thisembodiment;

FIG. 35 is a plan view of the vibration damping mount 21 e;

FIG. 36 is a sectional view of a spacer 90 a that is used in thisembodiment;

FIG. 37 is a plan view of the spacer 90 a;

FIG. 38 is a sectional view of a nip member 97 a that is used in thisembodiment;

FIG. 39 is a plan view of the nip member 97 a;

FIG. 40 is a sectional view of a conventional technique;

FIG. 41 is a sectional view showing a vibration damping mount 11; and

FIG. 42 is a sectional view showing a vibration damping mount 11 b.

DETAILED DESCRIPTION OF THE INVENTION

Even in the case in which an attachment portion of one object memberwith respect to a screw material has a size in a radial directionoverlapping a coupling member, a situation in which the attachmentportion of the one object member comes into contact with the couplingmember or the other object member retained by this coupling member isprevented. Consequently, an increase in noise due to the mutual contactis controlled.

In addition, a first direction, in which corrugate shape s formed on ametal heat shield extend, is set in a direction crossing a major ridgeequivalent portion of the metal heat shield. Thus, the corrugate shapesrealize a function of a rib with respect to a vibration around the ridgeequivalent portion. According to this rib action, a vibration of themetal heat shield can be controlled, occurrence of a crack in the metalheat shield can be prevented, and a quality of the metal heat shield canbe improved remarkably.

Embodiments of the present invention will be hereinafter explained.

First Embodiment

FIGS. 1 to 9 show a first embodiment of the present invention.

FIG. 1 is a sectional view schematically showing a state in which avibration damping mount 21 of this embodiment is used. FIG. 2 is a frontview of an engine 1 showing a structure forming a basis of the presentinvention. FIG. 3 is a sectional view of the engine 1 viewed from asection line X3-X3 in FIG. 2. FIG. 4 is an enlarged front view of ametal exhaust manifold heat shield (hereinafter referred to as heatshield) 1 of an embodiment of the present invention. FIG. 5 is asectional view of the heat shield viewed from a section line X5-X5 inFIG. 4. FIG. 6 is a sectional view of the heat shield viewed from asection line X6-X6 in FIG. 4. FIG. 7 is a sectional view of the heatshield viewed from a section line X7-X7 in FIG. 4. FIG. 8 is asimplified sectional view of the engine 1 viewed from a section lineX8-X8 in FIG. 2. FIG. 9 is a view illustrating characteristics of thisembodiment.

This embodiment will be hereinafter explained with reference to FIGS. 1to 9. Note that, since FIG. 2 has been referred to and explained in thesection of the conventional technique, a repeated explanation will beomitted. When FIG. 2 is referred to, the above-described referencenumerals and signs will be applied. In addition, in FIG. 2, a heatshield 3, which is an embodiment of the metal exhaust manifold heatshield of the present invention, is attached to an exhaust manifold 2mounted on the engine 1.

In this case, plural object members include the engine 1, the exhaustmanifold 2, and the heat shield 3. In the case of this embodiment, theexhaust manifold 2 constitutes-one object member, the heat shield 3constitutes the other object member, and the bolt 7 constitutes a screwmember. In this embodiment, as shown in FIG. 3, the heat shield 3 has astructure in which a damping member 6 having heat insulating propertiesis nipped between an inner 4 and an outer 5 consisting of a metal plate,respectively.

The heat shield 3 in this embodiment will be hereinafter explained. Asshown in FIG. 3, the heat shield 3 of this embodiment is constituted bystacking a pair of metal plates (e.g., NIMBUS manufactured by T&N) 4 and5 consisting of an aluminum alloy having a specific gravity of about 2.7and a heat resistant vibration damping member (hereinafter referred toas damping member) 6, which is nipped by the metal plates 4 and 5,consisting of inorganic fiber or the like, and is formed in athree-dimensional shape along an external shape of the exhaust manifold2. As shown in FIG. 8, the heat shield 3 includes a sidewall T1 and atop T2 that couples an entire periphery of an end of this sidewall T1.The sidewall T1 and the top T2 continue at an obtuse angle θ. In thisembodiment, the metal plates 4 and 5 are explained as including analuminum foil or an aluminum alloy foil or a thin plate consisting ofaluminum or an alloy of aluminum.

As shown in FIGS. 4 to 7, the metal plates 4 and 5 used in the heatshield 3 of this embodiment have a shape in which corrugate shapes 59having alternately repeated elevated portions 57 and valley portions 58extend in a first direction A1, and other corrugated shapes continue ina second direction A2 that is a direction crossing the first directionA1, preferably a direction perpendicular to the first direction A1. Asshown in FIGS. 4 to 7, in the elevated portions 57, first risingportions 60 and second rising portions 61 rise from the valley portions58 and are arranged alternately in a longitudinal direction thereof. Inaddition, as shown in FIGS. 4 to 6, in the valley portions 58, flatportions 62 and recessed portions 63 are arranged alternately.

As shown in FIG. 5, the first rising portions 60 include a pair ofsidewalls 64 and 65, which rise in a substantially trapezoid shape fromthe valley portions 58, and relatively flat tops 68, which are formed bycoupling tips of the sidewalls 64 and 65 each other. The first risingportions 60 are bent inward such that tips of the first rising portions60 are wider than base ends thereof.

On the other hand, as shown in FIG. 6, the second rising portions 61 areformed by crushing the first rising portions 60 in substantially a widthdirection by a predetermined degree. The second rising portions 61includes a pair of sidewalls 69 and 70, which rise from the flatportions 62, and recessed portions 73, which couple tips of thesidewalls 69 and 70 each other and are recessed to a lower side in FIG.6. Such second rising portions 61 and recessed portions 63 are formed soas to continue in a disconnected manner, respectively, in the seconddirection A2 that is a direction substantially perpendicular to thefirst direction Al in which the plural corrugate shapes 59 extend.

Therefore, as shown in FIGS. 5 and 6, projected portions of the elevatedportions 57 of the metal plate 5 are fit into inwardly bent innerperipheral portions of the elevated portions 57 of the metal plate 4. Inaddition, in the second rising portions 61, the sidewalls 69 and 70 arealso wider in tips than in the base ends thereof and formed in aninwardly bent shape. In such second rising portions 61, projectedportions of the second rising portions 61 of the metal plate 5 are fitinto inwardly bent inner peripheral portions of the second risingportions 61 of the metal plate 4. Consequently, the metal plates 4 and 5can be fixed to each other firmly without using any specific hold-downor fastener. The metal plates 4 and 5 are fixed each other in the samemanner even in the case in which the damping member 6 consisting ofinorganic fiber or the like is interposed between them. This is becausethe mutual coupling of the metal plates 4 and 5 depends upon amechanical engagement relation thereof.

The heat shield 3 is formed by stamping the metal plates 4 and 5, whichhave such a shape and nip the damping member 6, in a three-dimensionalshape along an external shape of the exhaust manifold 2.

A flange 78 with the corrugate shapes crushed by stamping is formed inan outer peripheral portion of the sidewall T1 of the heat shield 3formed in the three dimensional shape. As shown in FIG. 8, this flange78 is folded back to an inside of the heat shield 3, whereby afolded-back portion 79 is formed.

In the case in which this folded-back portion 79 is not formed, theouter peripheral portion of the heat shield 3 is in a state in whichsharp cut ends of the blanked metal plates 4 and 5 are directly exposedto the outside. Therefore, this folded-back portion 79 prevents anassembly worker, who works holding the heat shield 3, or a worker or ageneral user, who is likely to hold the heat shield 3 in the case ofmaintenance of a vehicle after manufacturing, from hurting fingers in aprocess of mounting the heat shield 3 on the exhaust manifold 2 of thevehicle engine 2 in a manufacturing process of the vehicle.

In addition, in this embodiment, crush object portions, for whichfolding-down, drilling, or inscription is required to be preformed inthe metal plates 4 and 5 having corrugate shapes, such as the flange 78,portions to be drilled, and portions to be inscribed of the heat shield3 are formed in a substantially tabular shape with the corrugate shapesin the crush object portions crushed by stamping.

Therefore, since the corrugate shapes of the crush object portionsincluding the flange 78 is formed in a substantially tabular shape, inthe case in which bending, drilling, inscription, or the like of theouter peripheral portion of the heat shield 3 is performed, the objectportions of such working can be treated in the same manner as thetabular metal plate.

In other words, when the working is performed, assuming a state in whichthe corrugate shapes remain, for example, in the case in which thefolding-back work is performed by stamping, a situation in which thecorrugate shapes under the folding-back work are crushed by the stampingis naturally anticipated. Thus, it is required to design a stamping dieon the assumption that the corrugate shapes are crushed, and a largeamount of labor and man-hours are required in the folding-back work.

On the other hand, in this embodiment, since the crush object portionscan be treated in the same manner as the tabular metal plate,workability in manufacturing the heat shield 3 is improved remarkably.

Other characteristics of the heat shield 3 of this embodiment will behereinafter explained with reference to FIGS. 2 and 8. As describedabove, the heat shield 3 of this embodiment is formed in athree-dimensional shape along a three-dimensional external shape of theexhaust manifold 2. Thus, as shown in FIGS. 2 and 8, one or more ridgeequivalent portions 80, which are bent portions of the metal plates 4and 5, are formed in the heat shield 3. In this embodiment, stamping toa three-dimensional shape is applied to the metal plates 4 and 5 suchthat the first direction A1, which is the longitudinal direction of thecorrugate shapes 59, is a direction crossing the major ridge equivalentportion 80 of these plural ridge equivalent portions 80.

Here, the major ridge equivalent portion 80 is a portion where bentportions having a relatively large curvature, which characterizes anoverall shape of the heat shield 3, continue. In other words, the majorridge equivalent portion 80 indicates a bent portion extending over arelatively long dimension, which substantially determines an externalshape of the heat shield 3, of bent portions of various sizes formed onthe heat shield 3.

When the heat shield 3 is mounted on the exhaust manifold 2, the heatshield 3 is also vibrated by transmission of a vibration from theexhaust manifold 2. When the heat shield 3 is vibrated by thisvibration, it is assumed that portions of the heat shield 3 on bothsides of the major ridge equivalent portion 80 are vibrated largely likewings of a butterfly around the major ridge equivalent portion 80. Whensuch a vibration occurs, metal fatigue is caused in portions near theridge equivalent portions 80 of the heat shield 3 due to repeatedbending, and a crack easily occurs in the portions.

On the other hand, in this embodiment, the first direction A1 of theplural corrugate shapes 59 formed on the heat shield 3 is set in adirection crossing the major ridge equivalent portion 80, preferably adirection perpendicular to the major ridge equivalent portion 80. Thus,the corrugate shape 59 realizes a function of a rib with respect to avibration around the ridge equivalent portion 80. Consequently, avibration of the heat shield 3 can be controlled, occurrence of a crackin the heat shield 3 can be prevented, and a quality of the heat shield3 can be improved remarkably.

In addition, with respect to a vibration that occurs in a direction inwhich the ridge equivalent portions 80 extend, the second risingportions 61 shown in FIGS. 4 to 6, which extend in a disconnected mannerin the second direction A2 and continue in the first direction A1, alsorealize a function of a rib and control the vibration.

The vibration damping mount 21, which is used in this embodiment, willbe hereinafter explained with reference to FIG. 1. The vibration dampingmount 21 of this embodiment includes: a substantially annular dampingmember 40, which is provided externally surrounding the bolt 7,constituted by a tabular material such as an expand metal of stainlesssteel, and has a zinc film formed on a surface thereof by, for example,Dacrotized (trademark) treatment; and a grommet 41 that is a couplingmember formed of an aluminum alloy and has substantially an S shapedsection. The grommet 41 has an insertion hole 42 through which the bolt7, which is screwed into the boss for bolt 10 of the exhaust manifold 2,is inserted.

In addition, the grommet 41 includes: a first retaining section 43having a shape with an inner peripheral edge of a circular metal platefolded back to an outer peripheral portion in order to retain the heatshield 3; a second retaining section 44 having a shape with an outerperipheral edge of the circular metal plate folded back to an innerperipheral portion in order to retain the damping member 40; and acoupling section 45 that is formed bending over the first retainingsection 43 and the second retaining section 44 and elastically couplesthe heat shield 3 and the damping member 40 via the first retainingsection 43 and the second retaining section 44 so as to be displacedfreely in an axial direction and a radial direction of the bolt 7.

In this embodiment, the coupling section 45 is a portion extending froma bent portion of the first retaining section 43 to a bent portion ofthe second retaining section 44. The second retaining section 44, thecoupling section 45, and the first retaining section 43 are provided inthis order from the exhaust manifold 2 side.

In addition, a collar member 22 formed of a galvanized steel plate isprovided between an inner periphery of the damping member 40 and thebolt 7. The collar member 22 includes a cylinder section 27 and flangesections 28 and 31 that are formed integrally at both ends in an axialdirection of the cylinder section 27, respectively. The collar member 22and the damping member 40 are formed and arranged such that gaps 37 inan axial direction and a radial direction of the bolt 7 are formedbetween the collar member 22 and the damping member 40.

Actions and effects of the vibration damping mount 21 will behereinafter explained. In the vibration damping mount 21, a vibration,which is generated from the exhaust manifold 2 and travels through thebolt 7, is transmitted to the heat shield 3 via the collar member 22,the damping member 40, and the grommet 41. In this case, the gaps 37 inthe axial direction and the radial direction of the bolt 7 are formedbetween the collar member 22 and the damping member 40.

Therefore, the vibration transmitted from the bolt 7 to the collarmember 22 is significantly controlled by the gaps 37 in a degree oftransmission to the collar member 22. Consequently, a buffer action ofthe vibration damping mount 21 with respect to a vibration is improvedremarkably, and a vibration control function of the heat shield 3 can beimproved remarkably.

In addition, the damping member 40 can perform a bending motion in theaxial direction of the bolt 7 easily because it is constituted by atabular material such as an expand metal. Therefore, the vibrationtransmitted to the damping member 40 from the collar member 22 isconverted into the bending motion of the damping member 40 and absorbed.In this regard, the buffer action of the vibration damping mount 21 isalso improved, and the damping function of the heat shield 3 is alsoimproved.

Further, in this embodiment, the second retaining section 43, thecoupling section 45, and the first retaining section 44 of the grommet41 are provided in this order from the exhaust manifold 2 side. In otherwords, the first retaining section 44 is located on the opposite side ofthe exhaust manifold 2 with respect to the damping member 40.

Therefore, even in the case in which the attachment boss 10 of theexhaust manifold 2 has a size in a radial direction overlapping thecollar member 22, a situation in which the attachment boss 10 comes intocontact with the grommet 41 or the heat shield 3 retained by the grommet41 is prevented. Consequently, an increase in noise due to the contactis controlled.

In addition, in the case in which contact of the attachment boss 10 andthe grommet 41 or the heat shield 3 is assumed, it is assumed that acontact portion of the grommet 41 with the attachment boss 10 wears dueto this contact to result in breakage. In this embodiment, occurrence ofsuch breakage is prevented. Consequently, a quality of the vibrationdamping mount 21 is improved remarkably.

Further, according to this embodiment, a zinc film having an ionizationtendency closer to that of aluminum than that of iron is formed on thesurface of the damping member 40. The collar member 22 is formed of agalvanized steel plate, and the grommet 41 is formed of an aluminumalloy. Therefore, in this embodiment, an action of reducing a differenceof t he ionization tendency between the damping member 40 and thegrommet 41 is realized. Consequently, occurrence of electrolysis in thegrommet 41 and the damping member 40 is controlled. In this regard, aquality of the vibration damping mount 21 is also improved remarkably.

Modification of the First Embodiment

As a modification of this embodiment, as shown in FIG. 25, the firstretaining section 43 of the grommet 41 may be fixed in abutment with theinner peripheral end of the heat shield 3 rather than being folded backas described above. In such a modification, it is evident that actionsand effects same as those in the above-mentioned embodiment arerealized. Therefore, this embodiment can realize actions and effectssame as those in the above-mentioned embodiment.

Second Embodiment

FIG. 10 is a sectional view schematically showing a vibration dampingmount 21 a according to a second embodiment of the present invention.FIG. 11 is a sectional view showing a principle of this embodiment. FIG.12 is an enlarged sectional view showing the principle of thisembodiment. FIG. 13 is a graph showing an effect of this embodiment.

The vibration damping mount 21 a according to the second embodiment ofthe present invention will be explained with reference to FIGS. 10 to13.

This embodiment is similar to the above-mentioned embodiment. Componentscorresponding to those in the above-mentioned embodiment are denoted bythe identical reference numerals and signs. In this embodiment, when theheat shield 3 is attached to the exhaust manifold 2, the vibrationdamping mount 21 a shown in FIG. 10 is used. The vibration damping mount21 a includes: a collar member 22; spring washers 23 and 24, which aredamping members with thickness t1, mounted on the collar member 22; andcircular grommets 25 and 26 mounted on outer peripheral edges of thespring washers 23 and 24, respectively.

The collar member 22 includes: a collar piece 29 that includes acylinder section 27 and a flange section 28 integrally formed at one endin an axial direction of the cylinder section 27; and a collar piece 32that includes a cylinder section 30 having a diameter larger than thecylinder section 27 and a flange section 31 integrally formed at one endin an axial direction of the cylinder section 30. The flanges 28 and 31are constituted to be apart from each other by a distance L1 shown inFIG. 10 in a state in which the cylinder section 27 is pressed and fixedin the cylinder section 30. Plate thicknesses of collar pieces 29 and32, and the like are selected such that the distance L1 satisfies thefollowing condition.L1>2×t1   (1)Therefore, when the spring washers 23 and 24 are mounted on the collarmember 22, as shown in FIG. 12, a gap 37 is formed between the flangesections 28 and 31 and the spring washers 23 and 24. The gap 37 has alength L2, which is calculated as follows, in the axial direction of thebolt 7.L2=L1−2×t1   (2)In addition, the collar member 22 having the flange sections 28 and 31and the cylinder section 33 is constituted by combining the collarpieces 29 and 32 as described above.

The spring washers 23 and 24 are formed of any one of plate-likematerials such as a metal plate, a punching metal, an expand metal, anda wire gauze. As an example, this embodiment will be explained assumingthat the spring washers 23 and 24 are formed of an expand metal. Thespring washers 23 and 24 are formed in substantially a circular shape.As shown in FIG. 12, an insertion hole 34 having an inner diameter L5,which is larger than an outer diameter L3 of the cylinder section 33 ofthe collar member 22 and smaller than an outer diameter L4 of the flangesections 28 and 31, is formed in the spring washers 23 and 24.L3<L5<L4   (3)Therefore, in order to mount such spring washers 23 and 24 on the collarmember 22, the collar member 22 is divided into two as shown in FIG. 10,and after mounting the spring washers 23 and 24 on, for example, thecollar piece 29, the collar piece 32 is pressed into the collar piece29. In this way, the spring washers 23 and 24 are mounted on the collarmember 22. Consequently, the gap 37 has a length (L5-L4) in the radialdirection of the bolt 7.

As shown in FIG. 10, grommets 25 and 26 are mounted on outer peripheriesof the spring washers 23 and 24. The grommets 25 and 26 are formed byfolding back an outer periphery of a circular metal plate consisting of,for example, a stainless steel plate or an aluminum alloy to the inside.Therefore, the grommets 25 and 26 are formed so as to wrap the outerperipheries of the spring washers 23 and 24.

In the case of this embodiment, the spring washers 23 and 24 are formedof an expand metal, and sharp cut ends project on the outer periphery ina state in which the spring washers 23 and 24 remain cut. By wrappingparts near the cut ends with the grommets 25 and 26, effects ofimproving the appearance of the spring washers 23 and 24 and retainingthe washers 23 and 24 to prevent a worker who works holding the springwashers 23 and 24 from hurting fingers are realized.

As shown in FIG. 10, the heat shield 3 is nipped and retained betweenthe spring washers 23 and 24 mounted with such grommets 25 and 26. Inorder to attach such a heat shield 3, which is mounted with thevibration damping mount 21 a, to the exhaust manifold 2, the bolt 7 isinserted through the inside of the cylinder section 33 of the collarmember 22 to be screwed into the attachment boss 10 or the like of theexhaust manifold 2. In this way, the heat shield 3 is attached to theexhaust manifold 2.

Actions of the vibration damping mount 21 a of this embodiment will behereinafter explained. According to the vibration damping mount 21 a ofthis embodiment, a vibration, which is generated from the exhaustmanifold 2 and travels through the bolt 7, is transmitted to the springwashers 23 and 24 via the collar member 22. In this case, the gap 37 isprovided between the pair of flange sections 28 and 31 of the collarmember 22 and the spring washers 23 and 24. Consequently, the collarmember 22 and the spring washers 23 and 24 are allowed to be relativelydisplaced in a direction parallel to and a direction crossing the axialdirection of the bolt 7. Therefore, the vibration from the bolt 7 isabsorbed by the relative displacement of the collar member 22 and thespring washers 23 and 24, whereby the transmission of the vibration tothe spring washers 23 and 24 can be controlled.

In addition, the vibration from the spring washers 23 and 24 istransmitted to the heat shield 3. In this case, since the spring washers23 and 24 are formed in a plate shape, the spring washers 23 and 24 bendin the axial direction of the bolt 7. Consequently, the transmission ofthe vibration from the spring washers 23 and 24 to the heat shield 3 iscontrolled.

The inventor performed an experiment concerning such an action andobtained measurement results shown in a graph in FIG. 13. In FIG. 13, ahorizontal axis shows a frequency, and a vertical axis shows anacceleration of a vibration. A curve g1 indicates a result of measuringa vibration of only the collar member 22, a curve g2 indicates a resultof measuring a vibration transmitted to the heat shield 3 of thevibration damping mount 11 having the structure shown in FIG. 29, acurve g3 indicates a result of measuring a vibration of a trial productwithout the gap 37 between the collar member 22 and the spring washers23 and 24, and a curve g4 indicates a result of measuring a vibration inthis embodiment.

As it is seen from these measurement results, a damping characteristicin all frequency bands of vibrations generated from the engine 1 and theexhaust manifold 2 is improved in the case in which the spring washers23 and 24 constituted by, for example, an expand metal of thisembodiment are used compared the case in which the felt-like dampingsheet shown in FIG. 29 is used. In particular, as in this embodiment,the damping characteristic is improved in the example of the structureprovided with the gap 37. Above all, the damping characteristic in arelatively low frequency band is improved.

In addition, the exhaust manifold 2 also serves as a heat source forcausing a combustion exhaust gas from the engine 1 to flow. In such acase, when heat from the exhaust manifold 2, which is transmittedthrough the bolt 7, is transmitted to the spring washers 23 and 24 viathe collar member 22, thermal conduction is blocked efficiently by thegap 37 between the pair of flange sections 28 and 31 of the collarmember 22 and the spring washers 23 and 24. Consequently, transmissionof the heat from the exhaust manifold 2 to the heat shield 3 is alsocontrolled efficiently.

As a result, in this embodiment, transmission of a vibration from theexhaust manifold 2, which is a vibration source, to the heat shield 3 iscontrolled efficiently. Thus, a situation in which the heat shield 3 isresonated by the transmitted vibration or metal fatigue occurs near theattachment portion of the heat shield 3 to the bolt 7 can be prevented,a situation of an increase in noise, occurrence of a crack in the heatshield 3, and the like can be eliminated, and a quality of the heatshield 3 can be improved remarkably. In addition, since the transmissionof heat from the exhaust manifold 2 can be controlled efficiently, thequality can also be improved in this regard.

Third Embodiment

FIG. 14 is a sectional view of a vibration damping mount 21 b of a thirdembodiment of the present invention. FIG. 15 is a sectional view of acomparative example of this embodiment. FIG. 16 is a sectional viewshowing characteristics of the vibration damping mount 21 b. FIG. 17 isa plan view of spring washers 23 and 24 of the vibration damping mount21 b. FIG. 18 is a perspective view of the spring washers 23 and 24.FIG. 19 is a perspective view of a comparative example for the vibrationdamping mount 21 b. FIG. 20 is a sectional view of the comparativeexample. FIG. 21 is a sectional view showing an operational example ofthe vibration damping mount 21 b. FIG. 22 is a sectional view showinganother operational example of the vibration damping mount 21 b. FIG. 23is a sectional view showing yet another operational example of thevibration damping mount 21 b. FIG. 24 is a graph illustrating an actionof this embodiment.

The vibration damping mount 21 b of this embodiment will be hereinafterexplained with reference to FIGS. 14 to 24.

This embodiment is similar to the second embodiment. Componentscorresponding to those in the second embodiment are denoted by theidentical reference numerals and signs. In addition, in FIGS. 15 to 23,only one spring washer 24 and one grommet 26 are shown forsimplification of the explanation. This embodiment is characterized inthat, in the vibration damping mount 21 a of the second embodiment, thegrommets 25 and 26 are not used, and the outer peripheries of the springwashers 23 and 24 are formed as free ends that vibrate freely.

As a comparative example of this embodiment, the vibration damping mount21 a of the second embodiment is cited with reference to FIG. 15. Asshown in FIG. 15, a length c in a radial direction of a partcontributing to the bending displacement of the spring washers 23 and 24is calculated as follows with respect to a projection length a, by whichinward ends in the radial direction of the grommets 25 and 26 projectfrom inward ends in the radial direction of the heat shield 3, and adistance b from the outer peripheries of the flange sections 28 and 31to the inward ends in the radial direction of the heat shield 3.c=b−a   (4)

On the other hand, in the vibration damping mount 21 b of thisembodiment, as shown in FIG. 16, since the outer peripheries of thespring washers 23 and 24 are not regulated by the grommets 25 and 26, alength d in the radial direction of the part contributing to the bendingdisplacement of the spring washers 23 and 24 is calculated as follows.d=b   (5)Therefore,d>c   (6)If the spring washers 23 and 24 of the vibration damping mount 21 b ofthis embodiment are used, a length in the radial direction of the bolt7, in which the spring washers 23 and 24 are bent and displaced, can beset large.

In this embodiment, the spring washers 23 and 24 are generallyplate-like members consisting of, for example, an expand metal, and asshown in FIGS. 17 and 18, the following relation is established among aninner diameter e and an outer diameter f of the spring washers 23 and 24in a natural state and an inner diameter e and an outer diameter f1 ofthe spring washers 23 and 24 in a bent state.f1<f   (7)On the other hand, as shown in FIGS. 19 and 20, concerning the innerdiameter e and the outer diameter f of the spring washers 23 and 24 inthe natural state and an outer diameter h of the grommets 25 and 26 andthe inner diameter e and the outer diameter f1 of the spring washers 23and 24 in the bent state and an outer diameter h1 of the grommets 25 and26, the outer diameters h and h1 are substantially equal.

This is because the outer peripheries of the spring washers 23 and 24are fixed by the grommets 25 and 26, and the grommets 25 and 26 areformed of a relatively hard material such as stainless steel asdescribed above.

Therefore, as shown in FIGS. 21 to 23, the spring washers 23 and 24 usedin the vibration damping mount 21 b of this embodiment are bent anddisplaced freely in an axial direction of the collar member 22, and adegree of bending of the spring washers 23 and 24 is increasedremarkably.

Therefore, a vibration, which is generated from the exhaust manifold 2and travels through the bolt 7, is transmitted to the spring washers 23and 24 via the collar member 22. In this case, in this embodiment, sincethe degree of bending of the spring washers 23 and 24 is increasedremarkably, the vibration is absorbed efficiently by the relativelylarge deformation of the spring washers 23 and 24, and transmission ofthe vibration to the heat shield 3 can be controlled.

The inventor performed an experiment concerning such an action andobtained measurement results shown in a graph in FIG. 24. In FIG. 24, ahorizontal axis shows a frequency, and a vertical axis shows anacceleration of a vibration. A curve g5 indicates a result of measuringa vibration of the vibration damping mount 21 a of the second embodimenthaving the grommets 25 and 26 mounted on the spring washers 23 and 24,and a curve g6 indicates a result of measuring a vibration in thisembodiment.

As it is seen from these measurement results, although the vibrationdamping mount 21 a of the second embodiment attains remarkable actionsand effects compared with the conventional technique as described above,the vibration damping mount 21 b of this embodiment attains a dampingcharacteristic more remarkable than that in the second embodiment.

In other words, in the vibration damping mount 21 b, the transmission ofa vibration from the exhaust manifold 2 to the heat shield 3 iscontrolled efficiently. Thus, a situation in which the heat shield 3 isresonated by the transmitted vibration or metal fatigue occurs near theattachment portion of the bolt 7 to the heat shield 3 can be prevented,a situation of an increase in noise, occurrence of a crack in the heatshield 3, and the like can be eliminated, and a quality of the heatshield 3 can be improved remarkably.

In addition, in this embodiment, since the spring washers 23 and 24formed in a plate shape are used, the spring washers 23 and 24 deform atthe time when a vibration is transmitted. The vibration is absorbed bythis deformation. Therefore, compared with the case in which the springwashers 23 and 24 consist of a felt-like material made of inorganicfiber or the like, a situation in which a damping member deterioratesdue to secular changes and self weights thereof, compression andrestoration characteristics fall, and a vibration control action fallscan be prevented. In addition, in the case of the felt-like material, aproblem is assumed in that the fiber decomposes and flies as timeelapses. However, in this embodiment, such a situation is alsoprevented.

Consequently, since the transmission of a vibration from the exhaustmanifold 2 to the heat shield 3 is controlled efficiently, actions andeffects same as those described above are attained.

Fourth Embodiment

FIG. 26 is a sectional view of a vibration damping mount 21 c of afourth embodiment of the present invention. This embodiment will behereinafter explained with reference to FIG. 26.

This embodiment is similar to the above-mentioned embodiments.Components corresponding to those in the above-mentioned embodiments aredenoted by the identical reference numerals and signs. This embodimentis characterized in that at least one of the spring washers 23 and 24used in the above-mentioned embodiments is used, and at least one of thespring washers 23 and 24 to be used is fixed to the heat shield 3 withspot welding or an arbitrary fixing technique. In the followingexplanation, as an example, a case of using only the spring washer 24 isassumed.

In this embodiment, as an attachment structure for attaching-the heatshield 3 to the exhaust manifold 2, a structure described below is used.In the heat shield 3, an insertion hole 8 with a diameter j forinserting the bolt 7 is provided, the spring washer 24 is arranged so asto cover the insertion hole 8, and the spring washer 24 is fixed to theheat shield 3 in a coupling portion 46 around the insertion hole 8 by atechnique such as spot welding or a rivet. The bolt 7 is insertedthrough the insertion hole 34 formed in this spring washer 24 andscrewed into an attachment boss 49 or the like of the exhaust manifold 2to attach the heat shield 3 to the exhaust manifold 2.

In this case, appropriate dimensions are selected for the diameter j ofthe insertion hole 8 of the heat shield 3, a diameter k of the bolt 7,and a diameter m of the attachment boss 49 such that a distance in aradial direction of a free vibration portion 48 is a distance of adegree allowing free vibration due to a spring property of the springwasher 24 to sufficiently contribute to the damping action as describedabove. Here, the free vibration portion 48 is an area where freevibration occurs due to bending displacement between a fixed portion 47,which is fixed between the attachment boss 49 with the diameter m of theexhaust manifold 2 and the bolt 7 with the diameter k of the springwasher 24, and the coupling portion 46.

In the vibration damping mount 21 c of such a structure, since thebuffer action according to the deformation of the spring washer 24 isalso realized, actions and effects same as those explained in theabove-mentioned embodiments are realized.

In addition, in any one of the vibration damping mounts 21, 21 a, 21 b,and 21 c of the above-mentioned embodiments, the damping member 40 maybe formed of a damping alloy body including at least Al with a contentof 6 to 10 weight % and the balance Fe or formed of an alloy materialincluding this damping alloy body.

As such a damping alloy body, for example, an Fe—Al damping alloymanufactured by Kabushiki Kaisha Urban Materials can be used. Thedamping alloy has an Al content of 6 to 10 weight % and, other than Al,includes Fe and inevitable impurities (Si of 0.1 weight % or less; Mn of0.1 weight % or less; C, N, S and 0 of 0.1 weight % or less in total).In addition, it is essential that an average particle diameter of acrystal of the damping alloy body is in a range of 300 to 700 μm. Athickness of this damping alloy body is, for example, about 0.1 to 1.0mm.

Since such a damping alloy body is a ferromagnetic material, a vibrationdamping mechanism therefor is according to magnetic/mechanical historyloss following irreversible movement of a magnetic wall.

As a typical comparative example, the inventor measured a dampingcoefficient, which indicates a damping capacity of vibration, for asteel plate, the damping alloy body, and a normal sandwich type dampingsteel plate, respectively. Results of the measurement are indicated bylines L1, L2 and L3 in FIG. 27. In this way, the inventor confirmed thata damping characteristic was improved remarkably in the damping alloybody compared with the normal metal plate.

Fifth Embodiment

A vibration damping mount 21 d according to a fifth embodiment of thepresent invention will be hereinafter explained.

FIG. 28 is a sectional view of the vibration damping mount 21 d of thisembodiment. FIG. 29 is a plan view of the vibration damping mount 21 din FIG. 28. FIG. 30 is a front view of a spacer 90 used in thisembodiment. FIG. 31 is a plan view of the spacer 90. FIG. 32 is asectional view of a nip member 97 used in this embodiment. FIG. 33 is aplan view of the nip member 97. This embodiment is similar to theabove-mentioned embodiments. Components corresponding to those in theabove-mentioned embodiments are denoted by the identical referencenumerals and signs.

The vibration-damping mount 21 d of this embodiment has an insertionhole 100, through which the bolt 7 is inserted, and includes the spacer90 formed of, for example, a metal material having a relatively lowfriction coefficient and a high hardness. The spacer 90 includes asubstantially cylindrical base section 91,in which the insertion hole100 is formed, and a sliding section 92, which integrally continuesoutwardly in a radial direction of the base section 91 and has a pair ofsliding surfaces 93 and 94, a distance between which in an axialdirection decreases toward a further outside in the radial direction.

The sliding surfaces 93 and 94 have a shape of a side of a truncatedcone and are constituted as relatively flat taper surfaces in the radialdirection. In the spacer 90, a stepped portion 99 elevated in the axialdirection of the bolt 7 is formed near a boundary of the sliding section92 and the base section 91.

The substantially annular nip member 97, which is constituted by atabular metal material having a spring property such as an expand metalof stainless steel and has a zinc film formed on a surface thereof by,for example, Dacrotized (trademark) treatment, is arranged in theoutside in the radial direction of the spacer 90. The nip member 97includes a pair of nip pieces 95 and 96 that are arranged increasinglyspaced apart from each other in the axial direction from an outside inthe radial direction toward an inside in the radial direction. The nippieces 95 and 96 are constituted so as to elastically nip the slidingsection 92 of the spacer 90 from sides opposed to each other in theaxial direction on the inside in the radial direction.

In addition, in parts near inside ends in the radial direction of thenip pieces 95 and 96, an elevated portion 98, which is engageable with astepped portion 99 at the time of displacement to the inside in theradial direction of the nip member 97, is formed with an interval L10 inthe radial direction from the stepped portion 99 of the spacer 90,respectively. The spacer 90 and the nip member 97 have such a structure,whereby mutual displacement at least in the radial direction is allowed.

In the outside in the radial direction of the nip member 97, a grommet41, which is a coupling member formed of, for example, an aluminum alloyand having substantially an S shaped section, is provided. The grommet41 has an insertion hole 42 through which the bolt 7 to be screwed intothe boss for bolt 10 of the exhaust manifold 2 is inserted.

In addition, grommet 41 includes: a first retaining section 43 having ashape with an inner peripheral edge of a circular metal plate foldedback to an outer peripheral portion in order to retain the heat shield3; a second retaining section 44 having a shape with an outer peripheraledge of the circular metal plate folded back to an inner peripheralportion in order to retain the nip member 97; and a coupling section 45that is formed bending over the first retaining section 43 and thesecond retaining section 44.

In this embodiment, the coupling section 45 is a portion extending forma bent portion of the first retaining section 43 to a bent portion ofthe second retaining section 44. The second retaining section 44, thecoupling section 45, and the first retaining section 43 are provided inthis order from the exhaust manifold 2 side. In addition, a through-holeis formed in a portion of the heat shield 3 where the vibration dampingmount 21 d is mounted. A part around this through-hole is theabove-mentioned substantially planar crush object portion where a crushportion 3 a is formed in advance. Therefore, the first retaining section43 of the grommet 41 retains this crush portion 3 a.

Actions and effects of the vibration damping mount 21 d will behereinafter explained. In the vibration damping mount 21 d, a vibration,which is generated from the exhaust manifold 2 and travels through thebolt 7, is transmitted to the heat shield 3 via the spacer 90, the nipmember 97, and the grommet 41.

In this case, in this embodiment, the sliding section 92 on the outsidein the radial direction of the spacer 90 is elastically nipped by thepair of nip pieces 95 and 96 of the nip member 97. The spacer 90 and thenip member 97 are allowed to be displaced from each other in the radialdirection as described above. Therefore, when the spacer 90 vibrates inthe radial direction, the nip member 97 and the spacer 90 are displacedfrom each other in the radial direction while the pair of nip pieces 95and 96 slide each other along the sliding section 92 of the spacer 90.Consequently, the vibration in the radial direction of the spacer 90 isabsorbed by the mutual displacement in the radial direction of thespacer 90 and the nip member 97.

In addition, the nip member 97 is constituted by the pair of nip pieces95 and 96 having a spring property. Moreover, the pair of nip pieces 95and 96 elastically nip the sliding section 92 of the spacer 90 and arenot fixed to the sliding section 92. Therefore, the spacer 90 can bevibrated and displaced in the axial direction while sliding with respectto the nip member 97 by a vibration in the axial direction of the spacer90. Moreover, since the spacer 90 is formed of a metal material having aspring property, the nip member 97 is bent and vibrated in the axialdirection by the vibration in the axial direction of the spacer 90.

Consequently, the vibration in the axial direction of the spacer 90 isabsorbed by the mutual displacement of the spacer 90 and the nip member97 involving mutual sliding and the displacement of the nip member 97itself. A degree of transmission of the vibration of the bolt 7 to theheat shield 3 can be controlled remarkably.

In addition, in this embodiment, the second retaining section 44, thecoupling section 45, and the first retaining section 43 of the grommet41 are provided in this order from the exhaust manifold 2 side. In otherwords, the first retaining section 43 is located on the opposite side ofthe exhaust manifold 2 with respect to the nip member 97.

Therefore, even in the case in which the attachment boss 10 of theexhaust manifold 2 has a size in a radial direction overlapping thegrommet 41, a situation in which the attachment boss 10 comes intocontact with the grommet 41 or the heat shield 3 retained by the grommet41 is prevented. Consequently, an increase in noise due to the contactis controlled.

In addition, in the case in which contact of the attachment boss 10 andthe grommet 41 or the heat shield 3 is assumed, it is assumed that acontact portion of the grommet 41 with the attachment boss 10 wears dueto this contact to result in breakage. In this embodiment, occurrence ofsuch breakage is prevented. Consequently, a quality of the vibrationdamping mount 21 d is improved remarkably.

Further, according to this embodiment, a zinc film having an ionizationtendency closer to that of aluminum than that of iron is formed on thesurface of the nip member 97. Therefore, even in the case in which thenip member 97 is formed of a stainless steel plate and the grommet 41 isformed of an aluminum alloy as described above, an action of reducing adifference of the ionization tendency between the nip member 97 and thegrommet 41 is realized. Consequently, occurrence of electrolysis in thegrommet 41 and the nip member 97 is controlled. In this regard, aquality of the vibration damping mount 21 d is also improved remarkably.

Moreover, in this embodiment, the stepped portion 99 is formed in thespacer 90, and the elevated portion 98 is formed in the pair of nippieces 95 and 96, respectively. Therefore, in the case in whichdisplacement in the radial direction of the spacer 90 and the nip member97 increases, the stepped portion 99 of the spacer 90 and the elevatedportion 98 of the nip member 97 come into abutment and engage with eachother to prevent excessive mutual displacement of the spacer 90 and thenip member 97. Consequently, occurrence of deficiency such as severecollision of the spacer 90 and the nip member 97 resulting in breakageof both of them can be prevented.

Sixth Embodiment

A vibration damping mount 21 e according to a sixth embodiment will behereinafter explained. FIG. 34 is a sectional view of the vibrationdamping mount 21 e of this embodiment. FIG. 35 is a plan view of thevibration damping mount 21 e in FIG. 34. FIG. 36 is a sectional view ofa spacer 90 a used in this embodiment. FIG. 37 is a plan view of thespacer 90 a. FIG. 38 is a sectional view of a nip member 97 a used inthis embodiment. FIG. 39 is a plan view of the nip member 97 a. Thisembodiment is similar to the fifth embodiment. Components correspondingto those in the fifth embodiment are denoted by the identical referencenumerals and signs.

A characteristic structure of this embodiment is that the spacer 90 aand the nip member 97 a of shapes and structures explained below areused instead of the spacer 90 and the nip member 97 used in the fifthembodiment.

The spacer 90 a of this embodiment includes a substantially cylindricalbase section 91 a, in which the insertion hole 100 is formed, and asliding section 92 a, which integrally continues outwardly in a radialdirection of the base section 91 a and has a sliding surface 92 bforming an arc surface with a sectional shape projected toward anoutside in a radial direction. More specifically, as shown in FIG. 36,as a shape of an outer peripheral surface, the sliding surface 92 bincludes arc surfaces 93 a and 94 a having a ¼ arc surface,respectively.

The substantially annular nip member 97 a, which is constituted by atabular metal material having a spring property such as an expand metalof stainless steel and has a zinc film formed on a surface thereof by,for example, Dacrotized,(trademark) treatment, is arranged in theoutside in the radial direction of the spacer 90 a. The nip member 97 aincludes a pair of nip pieces 95 a and 96 a that are arrangedincreasingly spaced apart from each other in the axial direction from anoutside in the radial direction toward an inside in the radialdirection. The nip pieces 95 a and 96 a are constituted so as toelastically nip the sliding section 92 a of the spacer 90 s from sidesopposed to each other in the axial direction on the inside in the radialdirection.

In addition, in parts near inside ends in the radial direction of thenip pieces 95 a and 96 a, a specific elevated shape such as the elevatedportion 98 of the nip member 97 in the fifth embodiment is not formed.

The vibration damping mount 21 e of this embodiment can realize actionsand effects equivalent to those in the above-mentioned embodiments andcan also realize specific actions and effects described below peculiarto this embodiment.

In the vibration damping mount 21 e of this embodiment, the slidingsurface 92 b of the spacer 90 a is formed as an arc surface projectedoutwardly in the radial direction. Therefore, when the spacer 90 a andthe nip member 97 a are displaced from each other while sliding, thepair of nip pieces 95 a and 96 a of the nip member 97 a are displacedsmoothly along the sliding surface 92 b forming the arc surface.

Consequently, even in the case in which displacement in the radialdirection of the spacer 90 a and the nip member 92 a is large, asituation in which the spacer 90 a and the nip member 92 a collideagainst each other is prevented, and occurrence of deficiency such asbreakage of both the spacer 90 a and the nip member 92 a can beprevented.

In addition, the pair of nip pieces 95 a and 96 a are displaced smoothlyalong the sliding surface 92 b forming the arc surface. Thus, the spacer90 a and the nip member 92 a are displaced from each other in the radialdirection. Moreover, the nip member 92 a can be displaced easily in theaxial direction as well around the part near the contact position of thespacer 90 a and the nip member 92 a.

Therefore, the nip member 92 a is displaced in the radial direction withrespect to the spacer 90 a and absorbs a radial direction component of avibration from the spacer 90 a. In addition, the nip member 92 a iseasily displaced in the axial direction with respect to the spacer 90 aand absorbs an axial direction component of the vibration from thespacer 90 a. Consequently, the vibration damping mount 21 e can controlthe vibration from the spacer 90 a remarkably.

The present invention is not limited to the above-mentioned embodimentsbut includes various modifications as long as the modifications do notdepart from the spirit of the present invention.

Even in the case in which an attachment portion of one object member toa screw member has a size in a radial direction overlapping a couplingmember, a situation in which the attachment portion of the one objectmember comes into contact with the coupling member or the other objectmember retained by the coupling member is prevented. Consequently, anincrease in noise, which is assumed in the case in which this contactoccurs, is controlled. The vibration damping mount of the presentinvention can be applied to applications in a wide range of technicalfields other than the engine for automobiles explained in the section ofthe embodiments of the present invention.

In addition, since a first direction, in which corrugate shapes formedon a metal heat shield extend, is set in a direction crossing a majorridge equivalent portion of the metal heat shield, the corrugate shapesrealize a function of a rib with respect to a vibration around the ridgeequivalent portion. According to this rib action, the vibration of themetal heat shield can be controlled, occurrence of a crack in the metalheat shield can be prevented, and a quality of the metal heat shield canbe improved remarkably. Consequently, the present invention can beapplied widely to many kinds of heat shields that are required to blockheat, vibration, and noise, and also required to be light.

1-5. (canceled)
 6. A vibration damping mount that is arranged betweenplural object members and damps transmission of a vibration from oneobject member, which is a vibration source, to another object member,the vibration damping mount comprising: a spacer that has asubstantially cylindrical base section having an insertion hole, throughwhich a screw member to be attached to the one object member isinserted, and a sliding section, which integrally continues outwardly ina radial direction of the base section and has a opposing slidingsurfaces with a distance between the sliding surfaces in an axialdirection decreasing with increasing outward distance in a radialdirection of the sliding surfaces; a nip member that is arrangedoutwardly in a radial direction of the spacer and includes a pair of nippieces, which are arranged increasingly spaced apart from each other inthe axial direction with decreasing inward distance in the radialdirection, the pair of nip pieces being formed of a spring materialwhich elastically nips the sliding surfaces of the sliding section ofthe spacer from sides opposed to each other, and said nip member beingconfigured to define a clearance at least in the radial direction withrespect to the spacer such that said nip member is radially displaceablerelative to the spacer; and a coupling member that includes a firstretaining section for retaining an outer circumferential portion of thenip member, a second retaining section for retaining the other objectmember, and a coupling section for coupling the first retaining sectionand the second retaining section, the first retaining section, thecoupling section, and the second retaining section being provided inthis order from the one object member side.
 7. A vibration damping mountaccording to claim 6, wherein the sliding surfaces are flat tapersurfaces tapering towards each other with increasing distance in theradial direction, a stepped portion elevated in the axial direction isformed at a boundary of the sliding section and the base section, andsaid nip member has an elevated portion, which is engageable with thestepped portion at a time of displacement to an inside in the radialdirection of the nip member, the elevated portion being is formed on aninner circumferential portion of said nip member and defining saidclearance between said elevated portion and said stepped portion. 8.(canceled)
 9. The vibration damping mount according to claim 7 whereinthe spring material includes zinc or a zinc compound disposed thereon.10-15. (canceled)